Conspiracy theories, cod mysticism and secret codes will always be with us, as the Dan Brown/Baigent and Leigh trial has illustrated. But it's a little known fact that the most celebrated exemplar of the form, the prophet Michel de Nostradamus, was also the Gordon Ramsay of the 16th century. He was particularly good at making jam. Nostradamus's "love jam" is apparently so powerful and efficacious that "if a man were to have a little of it in his mouth, and while having it in his mouth kissed a woman, or a woman him, and expelled it with his saliva, putting some of it in the other's mouth, it would suddenly cause ... a burning of her heart to perform the love-act".

The recipe is contained in Nostradamus's third book, the Traité des fardemens et confitures. This "Treatise on Make-Up and Jam" appeared in 1555, although the date on the manuscript is 1552. It's essentially a medical cookbook containing, as in many modern examples of cookbooks, the recipes of other people. There is one for curing the plague, for example, which is something you won't find in Nigella. Jamie Oliver would probably have a crack at it, were the government to ask him.

The book is based on knowledge acquired by Nostradamus (1503-1566) before he went to Montpellier to study for a medical doctorate in 1529. Prior to this he was a wandering apothecary.

The Traité offers useful recipes for marmalade ("candied orange peel ... that will be excellently tasty"), cherry jam (after a year the cherries are "just like they were on the day they were prepared"), quince jelly ("fit to set before a king") and pear preserve ("excellent enough to set before a prince").

There are also recipes for marzipan paste and sugar candy. To make toothpaste, use cuttlefish bone and calcined sea-snail shells, ground down thoroughly on a painter's marble slab. If your teeth are really rotten and decayed, as it were from too much sugar candy, try "blue clay".

Another recipe explains how to turn your hair blonde, and there are also laxatives based on both roses and rhubarb; but it is the "receipts" for curing plague and making people sleep with you that surely provide the greatest draw, even 450-odd years on.

To cure plague, "take one ounce of the sawdust or shavings of cypress-wood, as green as you can find, six ounces of Florentine violet-root, three ounces of cloves, three drams of sweet calamus, and six drams of aloes-wood. Reduce the whole to powder before it spoils."

Next, "take three or four hundred in-folded red roses ..." According to Nostradamus expert Peter Lemesurier, who made the translations used in this article, the 1995 Bloomsbury version of the Traité, entitled The Elixirs of Nostradamus, repeatedly translates "rose rouges incarnées" as "black orchids". Lemesurier's own The Unknown Nostradamus (O Books, 2003) sets out to tells the truth about the man, distancing him from centuries of fantasy. This puts him in a proper, midway, alchemical- medical context alongside John Dee and Paracelsus.

If his own words are to be believed, Nostradamus witnessed an outbreak of plague himself in Provence, and tried to treat some of its victims. "Among the [most] admirable things I saw, I think, was a woman who, even while I was paying a visit on her and calling to her through the window, replied to what I was saying - still through the window - while sewing herself unaided into her own shroud, starting with the feet." When the alarbes appeared, "which is what we in Provence call those who take the plague victims away and bury them", they found her dead, lying in the middle of the house - "with her sewing half-finished".

Nostradamus's official medical career did not last long. When he turned up at Montepellier, says Lemesurier, he was soon "booted out" for having, "as an apothecary, been rude about doctors!" By 1533 he was living in Agen in Aquitaine. There he became friends with François Rabelais, author of Gargantua and Pantagruel and a physician himself.

It may be the medical profession was motivated by jealousy, or perhaps the doctors at Montpellier thought Nostradamus's confections dangerous. After all, as he himself admits, the love jam is to die for. First invented "by Medea", it is said to have caused the death of the poet Lucretius.

As for the recipe: "Take three mandrake apples and go and cull them as soon as you see the sun rising, and wrap them in verbena leaves and the root of the mullein herb, and leave them alone until the following morning. Then take the weight of six grains of magnetite from the point where it repels the iron ... and pulverise it on the marble as finely as possible, sprinkling it a little with the juice of the mandrake apple ..."

Next, "Take the blood of seven male sparrows, bled via the left wing; of ambergris the weight of 57 barley seeds; seven grains of musk; of the core of the best cinnamon that can be found the weight of 377 barley seeds; of cloves and fine lignum aloes the weight of three deniers ['pence']; of the arms of an octopus one eyelet from each, preserved and prepared in honey; of mace the weight of 21 grains; of sweet flag the weight of 500 grains; of the root of Lyris Illyrica or Sclavonia ['Illyrian or Slavonian Lyre'] the weight of 700 grains; of the root of Apii Risus ['Bee's Laughter'] 31 grains; of Cretan wine double the weight of the whole; of the finest sugar the weight of 700 grains, which is just a little more than an ounce."

Mix all this together and pulverise it thoroughly in a marble mortar with a wooden pestle. Then boil it on a fire till it becomes like syrup ("take care above all that it is not a willow fire"). Then strain. Store in a gold or silver vessel.

The most important thing, if you should eat some love jam, is that you have sex that very day, as indeed you will. "For the increased production of semen that it produces rises to the brain and causes a madness that is called 'love-madness'" - as well, says Nostradamus, "as having other powerful effects". What these could be, the prophet does not vouchsafe, except to say they "rejoice" the person concerned. Maybe Dan Brown should try some love jam on his toast in the mornings. He looks as though he needs cheering up.